Quora is my newest favourite website. And it’s clear I’m not alone. After quietly building buzz through 2010 Quora has blow up, doubling in December and then doubling again in the first week of 2011.

I’m not surprised: Quora, a question-and-answer platform, is tapping into a really important trend, the rise of the interest graph alongside the social graph in online importance. Nathaniel Whittemore discussed this in a smart post a couple of months back:

If Facebook is the service with the internet’s most complete (visible) social graph, Twitter is the service with the internet’s most complete (visible) interest graph. “Following” a person — even one you don’t know — is an affirmation of your interest in their insights and recommendations. “Friending” someone is simply an act of acknowledging an existing relationship, that in many cases, has more to do with a previous shared experience (think: your freshman dorm) than with a really active shared interest.

At the time of Nathaniels post it did seem that Twitter offered the best example of the emerging interest graph. It’s non-reciprocal linking structure allows you to follow those that interest you, not just those you know, creating a blended social/interest graph. Hashtags further allowed you to follow specific conversations and connect with new people who share that interest.

Quora was built intentionally to capture the interest graph (Twitter was originally built to allow friends to keep track of each other) and so naturally takes this the next step, encouraging you to formally “follow” a variety of topics that interest you, from locations (“San Francisco”), industries (“media”, “tech”), companies (“Facebook”, “Twitter”), concepts (“crowdsourcing”), individuals (“Larry Lessig”, “Jack Dorsey”) and more (all examples are topics I follow). In addition you can follow specific questions, to get a notification each time there is a new response, and you can follow individuals, those you know or otherwise. Your feed is a blend of the topics, questions and people you follow.

This design influences your behavior on the site. There are people I follow on Twitter, because they are my friends and I’m interested in them, who I would not follow on Quora, simply because we do not share significant interest in common so their questions and answers are less likely to be relevant to me. While Quora is social I’m not there for a social experience per se, I’m interested in learning and, where possible, giving back in the form of answers.

The quality of the information being shared currently is phenomenal. It’s common to see founders of companies, even very large companies, responding to questions about that company. Steve Case responds to questions about early AOL decisions. Ashton Kutcher gives his opinion on how to get cast for a show. Evan Williams shares how Twitter managed to blow up at SxSW. Insiders share the thinking behind business deals or technology advances. It’s very skewered towards Silicon Valley/tech/startup but if it can maintain this quality across other topics it will become a vital site for many people.

For cause-focused organizations Quora also provides another powerful platform for sharing knowledge and stories, building authority and connecting with people who care about your issue. This has to be done respectfully, by passionate advocates of the organization, speaking as themselves. Credibility is built by thoughtfully providing answers and asking honest questions about things you seek to know. Admitting you don’t know everything is more likely to build support than pretending you do, and may even bring you unexpected answers and ideas.

It will be interesting to see how Quora evolves under the strain of growing users and the need to improve the user interface to encourage less tech-savvy participants. What I do know is that right now I’m leaning more useful, actionable information from Quora than anywhere else. For those that never likes the 140 character constraints of Twitter Quora might be the social network for you. Here's my response to a question on, where else?, Quora, Is Quora more interesting than Twitter right now? Why or why not?:

Absolutely. It's the best of twitter and blogging together in some ways (although I don't think it will replace or impact either). There is so much knowledge here, freely and cogently expressed, and this knowledge is vastly more searchable and accessible than that shared through Twitter. That said, I'm not sure Quora will be the relationship-building tool Twitter has been for me.